Products containing various organic and/or inorganic additives (actives) have been formulated for control of scale, corrosion, and deposition in commercial and industrial cooling water systems for many years. For example, many products commonly incorporated actives such as phosphate, zinc, and/or molybdate. These actives are used in field testing for control of product dosage, due to ready availability of quick, accurate, test methods.
Recent environmental restrictions on discharge of some actives, such as phosphate, zinc, and molybdate, as well as increased cost for molybdate, have restricted or eliminated such practice. In the case of molybdate, for example, the cost has increased from about $3.00/lb in 2003 to about $14.50/lb in 2005.
A second trend is the use of higher performance phosphonates, copolymers, and terpolymers, in products to enable the cooling water systems to be operated at higher cycles of concentration to minimize water use and discharge. Obtaining accurate field tests on these products using these components has become problematic. Therefore, these higher performance components currently have no usable field test or automatic control procedures, which can be used for control of dosage.
One response to this set of problems has been the development of fluorescent tracers, which are added to the products as a component specifically to allow field testing with subsequent manual or automatic control of dosage. Such technology is disclosed, for example, in U.S. Pat. Nos. 5,998,632 and 6,255,118. Further activity in this field is described in U.S. Pat. No. 6,750,328 B, where use of antibodies for detection of water treatment polymers is disclosed.
Problems associated with prior usages of an organic colorant as a tracer in cooling water formulations include: reactivity with actives in the product formulation; reactivity with stabilizers in the product formulation such as excess acid or caustic; stability towards halogens used to control biological growth in cooling water systems; stability towards non-oxidizing biocides used to control biological growth in cooling water systems; non-reactivity towards common constituents of cooling waters; detectability at low levels by low cost test methods; reasonable colorant unit cost; and so forth.
Therefore, there has been a need for solutions to such problems and shortcomings associated with prior use of water treatment compositions for cooling water systems.